In many steaming appliances, such as garment steamers, an electrical pump is used to deliver water onto a heated surface to generate steam. In some devices, water is delivered from a dosing head as a single stream or jet onto the heated surface. In some applications, the water is required to be spread over a larger area for the purpose of better heat extraction and steaming performance and so a spray nozzle or a multi jet nozzle is used.
Conventional spray nozzles typically have a fine opening to enable atomisation and large spread of water. Normally, the nozzles are made of metal or hard polymers. Water under pressure is forced through the spray nozzle and a resultant high velocity discharge of water results in a broad spray pattern. Pressure of water, the size of the nozzle opening and features to create a swirl near the outlet of the spray nozzle determine the spray droplet dimensions and the spray angle.
The higher the pressure, the better the atomisation and the spray angle but, consequently, the flow rate must also be higher. To lower the flow rate to values that the steam generator can support, the nozzle opening must be very small. Since a user of the garment steamer may use hard water during operation, scale can build up inside the nozzle, especially during rest periods when there is no water flow and the residual water gets evaporated due to the heat in the steam chamber, the nozzle can easily get clogged up with scale. Consequently, water flow is blocked by scale build up and the steaming operation is impaired or prevented.
A spray nozzle for spraying a liquid under pressure is known from U.S. Pat. No. 1,636,314 and comprises an elastomeric disc having a slit which opens under the pressure of the supplied fluid to provide a spray. However, as the slit is relatively small, the spray pattern is relatively narrow, and it can easily get blocked with scale.
A nozzle piece is known from U.S. Pat. No. 3,174,694 and includes a resilient discharge tube having a slit through which a solution is emitted when the discharge tube is manually bent.